H.264/AVC　is　the　newest　video　coding　standard　with　high　compression　efficiency.　Especially　it　adopts　traveling　algorithm　to　find　the　optimal　mode　for　intra-frame　prediction　in　spatial　field,　so　it　is　quite　complex　and　costs　very　long　encoding-time.　In　this　paper,　the　proposed　fast　mode　decision　scheme　consists　of　two　parts:　early　intra　mode　detection,　which　is　to　select　intra　4×4　or　intra　16×16　mode　for　each　MB　before　encoding　according　to　smoothness　characteristic,　and　fast　intra4×4　mode　decision,　which　is　to　reduce　choices　of　prediction　directions　from　9　to　3　by　SAD　of　Mode　0　to　Mode　2.　Experimental　results　show　that　without　the　variety　of　PSNR　basically,　the　compression　time　is　32.8%　less　than　the　original　algorithm,　and　only　increases　3.2%　bits-rate　on　average.　This　algorithm　improves　the　intra-frame　coding　efficiency,　and　is　especially　applicable　for　the　high　quality　and　complex　sequence.　©　2010　IEEE.